Compact electric machine with combined rotor carrier and clutch housing

ABSTRACT

An electric machine (10) includes a stator assembly (50) and a rotor (16) positioned within the stator assembly. The electric machine (10) further comprises a rotor carrier (20), and the rotor (16) is mounted on an outer surface (62) of the rotor carrier (20). The rotor carrier (20) includes a hub portion (22), a radial portion (24) extending from the hub portion (22), a first cylindrical portion (60) extending from the radial portion, and a second cylindrical portion (66) extending from the first cylindrical portion. The hub portion (22), the radial portion (24), the first cylindrical portion (60) and the second cylindrical portion (66) are provided as an integrally formed unitary component. An engine disconnect clutch (30) and a transmission clutch (40) are positioned within the rotor carrier (20).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication No. 62/474,492, filed Mar. 21, 2017, the entire contents ofwhich are incorporated herein by reference.

FIELD

This document relates to the field of electric machines, andparticularly electric machines with distributed stator windings for usein vehicles.

BACKGROUND

Dynamoelectric machines in automotive and other vehicle applicationsinclude alternators, alternator-starters, traction motors, hybrid drivemotors, as well as other applications. The stator of an electric machinetypically includes a cylindrical core formed as a stack of individuallaminations and having a number of circumferentially spaced slots thatextend axially through the stator core. A rotor assembly includes acenter shaft and is coaxial with the stator core. The stator core haswires wound thereon in the form of windings. The windings include axialsegments and end turn. The axial segments of the windings extend axiallythrough the slots of the core. The end turns connect the axial segmentsat opposing axial ends of the stator core, each end turn provided as apartial loop that extends circumferentially from one slot to another. Inthis general manner, a stator winding extends axially from end to end inselected ones of the plurality of stator core slots and extendscircumferentially between slots at the ends of the stator, according toa chosen wiring pattern.

The stator may be formed with any number of separate phase windings,such as three-phase, five-phase, six-phase, etc., and such determinesthe general wiring pattern to be implemented when winding the statorcore. Stator windings may be provided in different shapes andconfigurations, including concentrated stator windings and distributedstator windings.

Depending on the application for the electric machine, a number ofclutches may be associated with the electric machine. For example, inhybrid electric vehicles, it is common for an engine disconnect clutchand a launch clutch to be used in association with the electric machine.The engine disconnect clutch may be used to couple the electric machineto or decouple the electric machine from the internal combustion engineat different times. Similarly, the launch clutch may be used to couplethe electric machine to or decouple the electric machine from thetransmission at different times. Unfortunately, a large number of partsare required to build the electric machine and the associated clutches,thus adding to the cost of an assembly that includes the electricmachine and clutches. Additionally, the unit that includes the electricmachine and the associated clutches consumes a significant amount ofspace, and such space may be limited in various particular applications.

In view of the foregoing, it would be advantageous to provide anelectric machine and clutch unit having a reduced number of components,thereby saving significant costs to manufacture the unit. Additionally,it would be advantageous to provide an electric machine and clutch unitwith a reduced axial length, thereby saving space within the particularapplication environment. It would also be advantageous if such electricmachine and clutch unit provided for increased performance of theelectric machine and clutches.

SUMMARY

In accordance with one exemplary embodiment of the disclosure, there isprovided an electric machine including a stator assembly and a rotorpositioned within the stator assembly. The electric machine furthercomprises a rotor carrier wherein the rotor is mounted on an outersurface of the rotor carrier. The rotor carrier includes a hub portion,a radial portion extending from the hub portion, a first cylindricalportion extending from the radial portion, and a second cylindricalportion extending from the first cylindrical portion. The hub portion,the radial portion, the first cylindrical portion and the secondcylindrical portion are provided as an integrally formed unitarycomponent. An engine disconnect clutch is positioned within the rotorcarrier and engages an inner surface of the first cylindrical portion. Atransmission clutch is positioned within the rotor carrier and engagesan inner surface of the second cylindrical portion.

Pursuant to another exemplary embodiment of the disclosure, there isprovided a rotor carrier for an electric machine. The rotor carrierincludes a hub portion, a radial portion extending from the hub portion,and a circumferential portion extending from the radial portion. Thecircumferential portion is configured to engage a first clutch and asecond clutch. The hub portion, the radial portion, and thecircumferential portion are an integrally formed unitary component.

Pursuant to yet another exemplary embodiment of the disclosure, avehicle is provided comprising an engine having an output shaft. Anelectric machine is releasably coupled to the output shaft of the engineby an engine disconnect clutch. A transmission is releasably coupled tothe output shaft of the engine by a transmission clutch. At least onevehicle drive member is coupled to the transmission. The electricmachine includes a rotor and a stator assembly. The rotor is mounted ona rotor carrier including a hub portion, a radial portion extending fromthe hub portion, and a circumferential portion extending from the radialportion. The radial portion and the circumferential portion are anintegrally formed unitary component. The engine disconnect clutch andthe transmission clutch engage an inner surface of the circumferentialportion.

The above described features and advantages, as well as others, willbecome more readily apparent to those of ordinary skill in the art byreference to the following detailed description and accompanyingdrawings. While it would be desirable to provide a compact electricmachine that provides one or more of these or other advantageousfeatures, the teachings disclosed herein extend to those embodimentswhich fall within the scope of the appended claims, regardless ofwhether they accomplish one or more of the above-mentioned advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective cutaway view of an electric machine having arotor carrier and clutch housing;

FIG. 2 shows a cross-sectional view of one embodiment of a rotor carrierand clutch housing for the electric machine of FIG. 1;

FIG. 3 shows a cross-sectional view of another embodiment of a rotorcarrier and clutch housing for the electric machine of FIG. 1 whereinthe rotor carrier and clutch housing are combined;

FIG. 4 shows a cross-sectional view of another embodiment of thecombined rotor carrier and clutch housing for the electric machine ofFIG. 1;

FIG. 5 shows a perspective view of a first axial side of the combinedrotor carrier and clutch housing of FIG. 4;

FIG. 6 shows an cutaway view of the first axial side of the combinedrotor carrier and clutch housing of FIG. 5;

FIG. 7 shows the cutaway view of FIG. 5 rotated to show a second axialside of the combined rotor carrier and clutch housing;

FIG. 8 shows a perspective view of the second axial side of the combinedrotor carrier and clutch housing of FIG. 5;

FIG. 9 shows a vehicle with the electric machine of FIG. 1 positionedtherein; and

FIG. 10 shows a cross-sectional view of yet another embodiment of arotor carrier and clutch housing for an electric machine.

DESCRIPTION

With reference to FIG. 1, an electric machine 10 is shown. The electricmachine 10 includes a housing 12 that encloses a rotor 16 and a statorassembly 50. The rotor 16 is positioned on a rotor carrier 20, and anengine disconnect clutch 30 is positioned inside of the rotor 16 androtor carrier. A dual clutch 40 is positioned adjacent to the disconnectclutch 30. The dual clutch 40 includes a first/outer clutch 42 and asecond/inner clutch 44. The rotor carrier 20 is a unitary component thatprovides a rotor hub 22 and a clutch housing for both the enginedisconnect clutch 30 and the dual clutch 40.

The rotor 16 of the electric machine 10 may be provided in any ofvarious forms commonly known to those of skill in the art. In thedisclosed embodiment, the rotor 16 includes a plurality of permanentmagnets 18 embedded in a ferromagnetic material. However, it will berecognized that in other embodiments, the rotor carrier may beconfigured without permanent magnets and with rotor windings, such as aninduction, synchronous reluctance, or other type of electric machine.The rotor 16 is mounted on and fixed to the rotor carrier 20.

The rotor carrier 20 is generally cylindrical in shape and includes aradial portion 24 and a circumferential portion 26. The radial portion24 extends between the rotor hub 22 and the circumferential portion 26.The rotor 16 is mounted on the circumferential portion 26 of the rotorcarrier 20. The circumferential portion 26 also provides a clutchhousing for both the engine disconnect clutch 30 and the dual clutch 40.

The rotor carrier 20 is a unitary component such that the rotor hub 22,the radial portion 24 and the circumferential portion 26 are allintegrally formed from the same material and the various portions areall non-removable from one another without destruction of one or more ofthe respective portions. Accordingly, while different portions orsections of the rotor carrier may be identified, each portion isintegrally formed with one or more adjacent sections and is notconfigured for removal therefrom. In at least one embodiment, the rotorcarrier 20 is comprised of a metallic material such as steel, aluminum,or any of various other metals commonly utilized in electric motors andgenerators. In at least some embodiments, the rotor carrier may becomprised of a non-metallic material such as a relatively rigid polymermaterial with high heat resistance. The rotor carrier 20 may be formedby any of various means such as casting, flow-molding, etc.

As noted previously, the electric machine 10 in the embodiment of FIG. 1includes three clutches, including the engine disconnect clutch 30, theouter clutch 42 of the dual clutch 40, and the inner clutch 44 of thedual clutch 40. The engine disconnect clutch may also be referred toherein as clutch “C₀.” The outer clutch 42 of the dual clutch 40 is alaunch clutch and may be referred to herein as clutch “C₁.” The innerclutch 44 of the dual clutch 40 is a launch clutch for a reverse gear(or in some cases a 2^(nd) gear) and is also referred to herein asclutch “C₂.” Although clutches C₁ and C₂ are shown in FIG. 1 in a nestedconfiguration, it will be appreciated that clutches C₁ and C₂ may bearranged differently in other configurations, such as aside-by-side/parallel alignment. Furthermore, as noted in further detailbelow, including the embodiment of FIG. 10, one or more of clutches C₀,C₁ and C₂ may not be included in some embodiments.

With continued reference to FIG. 1, the engine disconnect clutch C₀ (30)is positioned at least partially within the rotor carrier 20. The clutchC₀ is configured to connect or disconnect the electric machine 10 and anengine (e.g., see the internal combustion engine 82 as shown in FIG. 7).In the embodiment of FIG. 1, the clutch C₀ is positioned completelywithin the rotor carrier 20, and the circumferential portion 26 of therotor carrier 20 serves as a housing for the clutch C₀. The clutch C₀may be provided in any of a number of forms, such as various types offriction clutches, or any of various other clutches. In at least oneembodiment, the clutch C₀ includes multiple plates 32, including a firstset of plates that are locked to the rotor carrier 20 and a second setof plates that are locked to an output shaft 34. When the clutch C₀ isopen with the plates 32 disengaged, the output shaft 34 is free torotate relative to the rotor carrier 20; when the clutch C₀ is closedwith the plates 32 engaged, the output shaft 34 is locked in rotationwith the rotor carrier 20.

With continued reference to FIG. 1, the dual clutch 40 is also packagedwithin in the housing 12 of the electric machine 10 adjacent to therotor 16. As noted previously, the dual clutch 40 includes clutch C₁(42) and a clutch C₂ (44). Clutch C₁ and clutch C₂ are each configuredto be engaged or disengaged with a transmission (e.g., see thetransmission 84 as shown in FIG. 7). Accordingly, the dual clutch 40 mayalso be referred to herein as a “transmission clutch.”

Each clutch C₁ and C₂ may be selectively opened (disengaged from thetransmission) or closed (engaged with the transmission) in order tochange the gear reduction in the transmission, thus providing for theswitching of gears within a vehicle. If both clutches C₁ and C₂ areopened when the engine is running, and the clutch C₀ is closed, theelectric machine 10 acts a generator that is driven by the engine duringthe times the vehicle is not being propelled by the transmission.Similar to clutch C₀, the dual clutch 40, including clutches C₁ and C₂,may also be provided in any of various forms. In the embodimentsdisclosed herein, clutches C₁ and C₂ are each provided as a frictionclutch including multiple plates.

A clutch control module 36 is provided on the outside of the housing 12of the electric machine. The clutch control module 36 includeselectronics that control whether the engine disconnect clutch 30 and thedual clutch 40 are open or closed at any given time. The clutch controlmodule 36 may also provide electronics configured to control thetransmission, as noted in further detail below.

The rotor 16 and the rotor carrier 20 of the electric machine 10 areconfigured to rotate within a stator assembly 50. The stator assembly 50includes a core 52 with windings 54 arranged on the core 52. The core 52is generally cylindrical in shape and is comprised of a plurality oflaminations. The laminations are generally annular in shape and arecomprised of a ferromagnetic material. The laminations are stacked oneon top of another to form the complete core 52. A plurality of axialslots are formed in the core 52. The slots are separated by teeth andextend in an axial direction through the stator core 52 from one end toan opposite end. The slots are configured to receive the stator windings54.

The stator windings 54 of the electric machine 10 are formed fromconductors inserted into the slots of the stator core 52. The statorwindings 54 include a first end turn portion 56, a second end turnportion 58, and an in-slot portion. The first end turn portion 56extends from one end of the stator core 52, and the second end turnportion 58 extends from the opposite end of the stator core 52. Thein-slot portion of the stator windings 54 extend through the slots inthe stator core 52 from one end to the opposite end.

With reference now to FIG. 2, a cross-sectional view of an alternativearrangement for the electric machine 10 is shown. In this embodiment,the rotor carrier 20 is connected to the rotor hub 22, but is notintegrally formed with the rotor hub 22 and various clutch housings. Inthe arrangement of FIG. 2, the rotor carrier 20 is generally cylindricalin shape and includes a radial portion 24 and a circumferential portion26. The radial portion 24 extends between the rotor hub 22 and thecircumferential portion 26. The rotor 16 is mounted on thecircumferential portion 26 of the rotor carrier 20 and is rotatablewithin the stator assembly 50. The arrangement of FIG. 2 includes afirst clutch housing 70 and a second clutch housing 74.

The first clutch housing 70 in the arrangement of FIG. 2 provides ahousing for the engine disconnect clutch 30. The first clutch housing 70is connected to the rotor hub 22 and is positioned within the rotorcarrier 20. The first clutch housing 70 extends radially outward andengages the outer diameter of the clutch plates of the engine disconnectclutch 30. Fluid from line 71 controls the pressure member 72 (e.g., apiston member). When the pressure member 72 applies pressure to theplates of the engine disconnect clutch 30, the clutch is closed and thefirst clutch housing 70 and connected rotor carrier 20 are locked to theengine output shaft 73 via the plates of the engine disconnect clutch30. When pressure is released from the plates of the engine disconnectclutch 30, the clutch is opened and the rotor carrier 20 and rotor hub22 are freely rotatable relative to the engine output shaft 73.

The second clutch housing 74 in the arrangement of FIG. 2 provides ahousing for the dual clutch 40 which is positioned axially adjacent tothe rotor 16 and rotor carrier 20. The second clutch housing 74 includesa first portion 74 a and a second portion 74 b. The first portion 74 ais connected to the rotor hub 22 and extends radially alongside therotor carrier 20. The second portion 74 b is connected to the firstportion 74 a via a weld or other connection and engages the outerdiameter of the clutch plates of clutch C₁ (42). Fluid from one or morelines, such as line 75, controls the pressure members 76 a and 76 b.Pressure member 76 a controls operation of the outer clutch C₁, andpressure member 76 b controls operation of the inner clutch C₂. When thepressure member 76 a applies pressure to the plates of clutch C₁, theclutch is closed and locked to the transmission input shaft 77. Whenpressure is released from the plates of clutch C₁, the clutch C₁ isopened and freely rotatable relative to the engine output shaft 73. Whenthe pressure member 76 b applies pressure to the plates of clutch C₂,the clutch is closed and locked to the transmission input shaft 77. Whenpressure is released from the plates of clutch C₂, the clutch C₂ isopened and freely rotatable relative to the engine output shaft 73.

As described above, in the arrangement of FIG. 2 the rotor carrier 20,the rotor hub 22, the first clutch housing 70 and the second clutchhousing 74 are not provided as a unitary component. However, FIG. 3discloses an embodiment of a compact electric machine 10 wherein therotor carrier 20, the rotor hub 22, the first clutch housing 70, and thesecond clutch housing 74 are all provided as an integrally formedunitary component. The rotor carrier of FIG. 3 is shown incross-hatching and includes an integrally formed rotor hub 22, a radialportion 24 and a circumferential portion 26. The radial portion 24extends radially outward from the hub 22 to the circumferential portion26. The circumferential portion 26 includes a first cylindrical portion60 and a second cylindrical portion 66. The radial portion 24 isconnected to the first cylindrical portion 60. The second cylindricalportion 66 extends axially away from the first cylindrical portion 60and has a greater diameter than the first cylindrical portion 60. Anouter wall 65 extends in the radial direction between the firstcylindrical portion 60 and the second cylindrical portion 66. The radialportion 24 that extends from the rotor hub 22 to the first cylindricalwall is positioned between the engine disconnect clutch 30 and the dualclutch and separates the engine disconnect clutch 30 from the dualclutch 40 within the rotor carrier 20.

With continued reference to FIG. 3, the first cylindrical portion 60 ofthe circumferential portion 26 of the rotor carrier 20 is substantiallycylindrical in shape and includes an outer surface 62 and an innersurface 64. The rotor 16 (not shown in FIG. 3) is mounted on the outersurface 62 of the first cylindrical portion 60. A number of the platesof the engine disconnect clutch 30 engage the inner surface 64 of thefirst cylindrical portion 60 of the rotor carrier 20. Similarly, thesecond cylindrical portion 66 is substantially cylindrical in shape andincludes an outer surface and an inner surface 68. A number of theplates of clutch C₁ engage the inner surface 68 of the secondcylindrical portion 66 of the rotor carrier 20. Accordingly, the rotorcarrier 20 in the embodiment of FIG. 3 not only provides a rotor mountand rotor hub, but also provides a combined clutch housing for both theengine disconnect clutch 30 and the dual clutch 40.

Advantageously, the embodiment of the combined rotor carrier, rotor huband clutch housing of FIG. 3 allows for the reduction of a number ofcomponents over the arrangement of FIG. 2. In particular, the firstclutch housing 70 and the portion 74 a of the second clutch housing 74of FIG. 2 are completely removed in the embodiment of FIG. 3. Thisallows the embodiment of the electric machine and clutch arrangement ofFIG. 3 to have a reduced axial length in comparison to the arrangementof FIG. 2. Additionally, because the engine disconnect clutch 30 isconfigured to engage the inner surface 64 of the rotor carrier 20, thesize of the friction plates of the engine disconnect clutch 30 can beincreased. Because the size of the friction plates is increased, thenumber of friction plates can be reduced. In particular, the effectivefriction radius is increased by the enlargement of the plates, resultingin an equivalent torque transfer with the same pressure applied by thereduced number of friction interfaces.

With reference now to FIG. 4 yet another embodiment of a rotor carrier20, with a combined rotor hub and clutch housing is shown. Theembodiment of the rotor carrier 20 in FIG. 4 is similar to that of FIG.3, and includes a rotor hub 22, a radial portion 24, and acircumferential portion 26. The rotor hub 22 includes a first lip 27providing a first round surface (i.e., cylindrical surface) configuredto engage a first bearing 37 and a second lip 28 providing a secondround surface configured to engage a second bearing 38. The radialportion 24 extends radially outward from the rotor hub 22 to thecircumferential portion 26. The circumferential portion 26 includes afirst cylindrical portion 60 and a second cylindrical portion 66. Unlikethe embodiment of FIG. 3, the radial portion 24 of the rotor carrier 20in the embodiment of FIG. 4 is not positioned between the enginedisconnect clutch 30 and the dual clutch 40. Instead, the radial portion24 of the rotor carrier 20 is positioned at an end of the rotor carrier20 and both the engine disconnect clutch 30 and the dual clutch 40 areon the same side of the radial portion 24. With this arrangement, thesecond cylindrical portion 66 of the circumferential portion 26 extendsaxially from one end of the first cylindrical portion 60, and the radialportion 24 extends radially another end of the first circumferentialportion 60.

With continued reference to FIG. 4, the first cylindrical portion 60 ofthe circumferential portion 26 of the rotor carrier 20 is generallycylindrical in shape and includes an outer surface 62 and an innersurface 64. The rotor 16 is mounted on the outer surface 62 of the firstcylindrical portion 60. Some of the plates of the engine disconnectclutch 30 engage the inner surface 64 of the first cylindrical portion60 of the rotor carrier 20. Other plates of the engine disconnect clutch30 engage a member that is connected to the engine output shaft 73.Similarly, the second cylindrical portion 66 is generally cylindrical inshape and includes an outer surface 67 and an inner surface 68. Some ofthe plates of clutch C₁ engage the inner surface 68 of the secondcylindrical portion 66 of the rotor carrier 20. Other plates of thelaunch clutch are connected to one of the transmission input shafts. Forexample, in a transmission with a dual clutch, such as that shown inFIGS. 2-4, there are typically two transmission input shafts, with theouter clutch C₁ attached to one transmission input shaft and the innerclutch C₂ attached to another transmission input shaft.

Based on the foregoing description, it will be recognized that the rotorcarrier 20 in the embodiments of FIGS. 3 and 4 not only provides thefunction of retaining the rotor 16, but also provides a rotor hub 22 aswell as a combined clutch housing for both the engine disconnect clutch30 and the dual clutch 40. Advantageously, the rotor carrier 20 with acombined rotor hub and clutch housing, such as that shown in FIGS. 3 and4, utilizes less material and has fewer parts than other arrangements,and may therefore be manufactured for less cost. Additionally, similarto the embodiment of FIG. 3, the electric machine 10 having a rotorcarrier 20 with a combined rotor hub and clutch housing as shown in FIG.4 provides for an arrangement for an electric machine with a reducedaxial length. For example, the arrangement of FIG. 4 reduces the axiallength of the electric machine 10 by more than 20 mm over thearrangement of FIG. 2. As noted previously, this not only reduces thecost of the electric machine but also allows the electric machine to beused in applications with limited space configurations.

With reference now to FIGS. 5-8, the rotor carrier 20 is shown inisolation. The rotor carrier 20 is generally cylindrical in shape andincludes a rotor hub 22 (which is also referred to herein as a (hubportion 22), a radial portion 24 extending in a generally radialdirection from the hub portion 22, and a circumferential portion 26extending in a generally axial direction from the radial portion 24. Asnoted previously, the hub portion 22, radial portion 24 and thecircumferential portion 26 are all comprised of a common material (e.g.,a metal or polymer material) formed as a unitary structure wherein theradial portion 24 is integral with both the hub portion 22 and thecircumferential portion 26. Accordingly, none of the hub portion 22,radial portion 24 or circumferential portion 26 may be removed from anyother portion without destruction of the unitary component as a whole.

With continued reference to FIGS. 5-8, the hub portion 22 is defined bya circular opening 23 and is configured to receive an output shaft of aninternal combustion engine (e.g., see output shaft 73 of FIG. 3). Thehub portion 22 includes a first lip 27 and a second lip 28. The firstlip 27 is configured to engage a first bearing (e.g., see bearing 37 ofFIG. 4) positioned between the output shaft and the first lip 27. Thesecond lip 28 is configured to engage a second bearing (e.g., seebearing 38 of FIG. 4) positioned between the output shaft and the secondlip 28.

The radial portion 24 extends radially outward from the hub portion 22.In the embodiment of FIGS. 5-8, the radial portion 24 includes a firstradial wall 90 and a second radial wall 92, with an axial connectingwall 94 extending between the first radial wall 90 and the second radialwall 92. When positioned in the electric machine 10 in a vehicle, theradial portion 24 faces an internal combustion engine and provides acovering for the clutches 30, 40 at one end of the electric machine. Theradial portion 24 extends a radial distance between the hub portion 22and the circumferential portion 24.

The circumferential portion 26 of the rotor carrier 20 includes a firstcylindrical portion 60 and a second cylindrical portion 66. One end ofthe first cylindrical portion 60 is connected to the radial portion 24and an opposite end of the first cylindrical portion 60 is connected tothe second cylindrical portion 66. The second cylindrical portion 66 hasa greater diameter than the first cylindrical portion 60. An outer wall65 extends in a radial direction between the first cylindrical portion60 and the second cylindrical portion 66, thereby bridging thedifference in the diameters of the first cylindrical portion 60 and thesecond cylindrical portion.

Together, the hub portion 22, the radial portion 24, and thecircumferential portion 26 of the rotor carrier 20 form a cup-likestructure defining an interior space. Various components are arrangedwithin the interior space, including the engine disconnect clutch 30 andthe dual clutch 40. An inner surface 64 of the first cylindrical portion60 is configured to engage the engine disconnect clutch 30. An innersurface 68 of the second cylindrical portion 66 is configured to engagethe dual clutch 40, and particularly clutch C₁. On the outside of therotor carrier 20, an outer surface 62 of the first cylindrical portion60 is configured to provide a mount for the rotor 16 of the electricmachine 10.

With reference now to FIG. 9, in at least one embodiment, the electricmachine 10 with the unitary rotor carrier 20 is positioned within avehicle and particularly a hybrid electric vehicle (HEV) 80. The HEV 80includes an engine 82, the electric machine 10, a transmission 84, oneor more differentials 86, and vehicle drive members in the form ofvehicle wheels 88. The electric machine 10 is positioned between theengine 82 and the transmission 84. As described above, the electricmachine 10 includes a rotor carrier 20 with a combined rotor hub andclutch housing. A number of clutches are retained with the rotor carrier20 including an engine disconnect clutch 30 and a dual clutch 40. Theengine disconnect clutch 30 couples or uncouples the engine 82 to orfrom the electric machine 10, and the dual clutch 40 couples oruncouples the transmission 84 to or from the electric machine 10.

The engine 82 in the embodiment of FIG. 9 is an engine that may be usedin association with vehicles, such as an internal combustion engine. Itwill be recognized that in at least one alternative embodiment, theengine 82 is provided by an alternative power source, such as acompressed air engine, turbine or other power source. Furthermore, theengine 82 may be configured to use any of various fuel sources such asgasoline, diesel, biofuel, etc. The engine 82 includes an output shaft83 that is coupled to the transmission 84 via the clutches 30 and 40associated with the electric machine 10.

The transmission 84 may be any of various types of transmissions, suchas an automatic step-ratio transmission, a continuously variabletransmission, etc. The transmission is connected to the drive wheels 88in a conventional manner which may include one or more differentials 86,as shown in FIG. 9. The transmission may provide the vehicle with twodrive wheels (e.g., front wheel drive or rear wheel drive) or four drivewheels (e.g., four wheel drive). The transmission is controlled using atransmission control unit to operate on a shift schedule that connectsand disconnects elements within the gear box of the transmission tocontrol the ratio between the transmission output and the transmissioninput. In at least one embodiment, the transmission control unit isprovided by the control module 36 and is also configured to controloperation of the engine disconnect clutch 30 and the dual clutch 40, aswell as various other components within the transmission 84 or thehousing 12 of the electric machine.

A relatively small space exists in the vehicle 80 between the engine 82and the transmission 84. The space may be defined in general by an axialdimension and two radial dimensions. The axial dimension tends to beparticularly limiting as a relatively small distance is provided betweenthe engine and the transmission. For example in many HEVs the axialdistance (e.g., d_(a) as shown in FIG. 9) between the engine and thetransmission is less than 160 mm. In at least one embodiment, the axialdistance d_(a) is less than 135 mm. In these HEVs, the compactconfiguration of the electric machine 10 including a rotor 16 and statorassembly 50 with commonly housed engine disconnect clutch 30 and dualclutch 40, allows the entire housing 12 of the electric machine 10 tofit between the engine 82 and the transmission 84. The compactconfiguration of the electric machine is attributed in part to theunitary rotor carrier 20 with a combined rotor hub and clutch housing.

The foregoing detailed description of one or more exemplary embodimentsof the electric machine with compact configuration has been presentedherein by way of example only and not limitation. It will be recognizedthat there are advantages to certain individual features and functionsdescribed herein that may be obtained without incorporating otherfeatures and functions described herein. For example, while theforegoing embodiments included specific clutch arrangements, in variousembodiments the electric machine with compact configuration may includedifferent clutch arrangements.

FIG. 10, illustrates one example of such an electric machine 10 thatincludes a combined launch clutch and disconnect clutch 35. Similar tothe electric machines of FIGS. 1-4, the electric machine 10 includes arotor 16 positioned within a stator assembly 50. The stator assemblyincludes a core 52 with windings 54. The rotor is retained by a rotorcarrier 20. The rotor carrier 20 is a unitary component that extendsfrom an engine output shaft to the rotor 16. Similar to the embodimentof FIG. 4, the rotor carrier 20 shown in FIG. 10 includes a hub portion22 that forms part of the engine output shaft 73, a radial portion 24,and a cylindrical portion 26. Unlike the embodiment of FIG. 4, the rotorcarrier 20 shown in FIG. 10 does not include a second cylindricalportion because the rotor carrier is used in an arrangement with thecombined launch clutch and disconnect clutch 35. This clutch arrangementis advantageous for certain applications, such as a torque converterreplacement.

In view of the foregoing, it will be recognized that variousalternatives, modifications, variations, or improvements of theabove-disclosed exemplary embodiments and other features and functions,or alternatives thereof, may be desirably combined into many otherdifferent embodiments, systems or applications. As yet another example,although the HEV disclosed herein is an automobile HEV, it will berecognized that the vehicle may be provided in different forms such as aboat, aircraft, or any of various other vehicles.

Presently unforeseen or unanticipated alternatives, modifications,variations, or improvements therein may be subsequently made by thoseskilled in the art which are also intended to be encompassed by theappended claims. Therefore, the spirit and scope of any appended claimsshould not be limited to the description of the exemplary embodimentscontained herein.

What is claimed is:
 1. An electric machine (10) comprising: a statorassembly (50); a rotor (16) positioned within the stator assembly; arotor carrier (20) wherein the rotor (16) is mounted on an outer surface(62) of the rotor carrier, the rotor carrier (20) including a hubportion (22), a radial portion (24) extending from the hub portion (22),a first cylindrical portion (60) extending from the radial portion, anda second cylindrical portion (66) extending from the first cylindricalportion, wherein the hub portion (22), the radial portion (24), thefirst cylindrical portion (60) and the second cylindrical portion (66)are an integrally formed unitary component; an engine disconnect clutch(30) positioned within the rotor carrier (20) and engaging an innersurface (64) of the first cylindrical portion (60); and a transmissionclutch positioned within the rotor carrier (20) and engaging an innersurface (68) of the second cylindrical portion (60).
 2. The electricmachine of claim 1, the hub portion (22) including a first surface (27)engaging a first bearing (37) and a second surface (28) engaging asecond bearing (38).
 3. The electric machine of claim 1 wherein thesecond cylindrical portion (66) has a greater diameter than the firstcylindrical portion (60).
 4. The electric machine of claim 1 wherein thetransmission clutch (40) includes a outer clutch (42) positioned withinthe second cylindrical portion (66) of the rotor carrier and an innerclutch (44) positioned within the first cylindrical portion (60) of therotor carrier.
 5. The electric machine of claim 1 wherein the radialportion (24) extends from one end of the first cylindrical portion (60),and the second cylindrical portion (66) extends from an opposite end ofthe first cylindrical portion (60).
 6. A rotor carrier (20) for anelectric machine, the rotor carrier (20) comprising: a hub portion (22);a radial portion (24) extending from the hub portion (22); and acircumferential portion (26) extending from the radial portion andconfigured to engage a first clutch (30) and a second clutch (40);wherein the hub portion (22), the radial portion (24), and thecircumferential portion (26) are an integrally formed unitary component.7. The rotor carrier of claim 6 wherein the circumferential portionincludes a first cylindrical portion (60) and a second cylindricalportion (66), the first cylindrical portion (60) extending from theradial portion (24) and configured to engage the first clutch (30), andthe second cylindrical portion (66) extending from the first cylindricalportion (60) and configured to engage a second clutch (40).
 8. The rotorcarrier of claim 7 wherein the second cylindrical portion (66) has agreater diameter than the first cylindrical portion (60).
 9. The rotorcarrier of claim 8 wherein the radial portion (24) extends from one endof the first cylindrical portion (60), and the second cylindricalportion (66) extends from an opposite end of the first cylindricalportion (60).
 10. The rotor carrier of claim 6 wherein the hub portion(22) includes a first lip (27) configured to engage a first bearing(37), and a second lip (28) configured to engage a second bearing (38).11. A vehicle (80) comprising: an engine (82) having an output shaft(83); an electric machine releasably coupled to the output shaft (83) ofthe engine (82) by an engine disconnect clutch (30); a transmission (84)releasably coupled to the output shaft (83) of the engine (82) by atransmission clutch (40); and at least one vehicle drive member (88)coupled to the transmission (84); wherein the electric machine (10)includes a rotor (16) and a stator assembly (50), the rotor (16) mountedon a rotor carrier (20) including a hub portion (22), a radial portion(24) extending from the hub portion (22), and a circumferential portion(26) extending from the radial portion, wherein the engine disconnectclutch (30) and the transmission clutch (40) engage an inner surface ofthe circumferential portion (26), and wherein the radial portion (24)and the circumferential portion (26) are an integrally formed unitarycomponent.
 12. The vehicle of claim 11 wherein the circumferentialportion (26) of the rotor carrier (20) includes a first cylindricalportion (60) and a second cylindrical portion (66), the firstcylindrical portion (60) extending from the radial portion (24) andengaging the engine disconnect clutch (30), and the second cylindricalportion (66) extending from the first cylindrical portion (60) andengaging the transmission clutch (40).
 13. The vehicle of claim 12wherein the second cylindrical portion (66) has a greater diameter thanthe first cylindrical portion (60).
 14. The vehicle of claim 12 whereinthe radial portion (24) extends from one end of the first cylindricalportion (60), and the second cylindrical portion (66) extends from anopposite end of the first cylindrical portion (60).
 15. The vehicle ofclaim 11 wherein the hub portion (22) includes a first surface (27)configured to engage a first bearing (37) and a second surface (28)configured to engage a second bearing (38), the first bearing (37) andthe second bearing (38) provided between the hub portion (22) and theoutput shaft (83).